Period getting weird

My period for the last two months has started a few days late. After it started my bleeding was either very light or spotting and only lasted for 2-3 days instead of my usual 4. I've taken pregnancy tests each time it didn't show on time and all have been negative. I'm 26 and have had a regular period pretty much since I started as a kid. I haven't been on birth control for about a year either. My periods arent really painful either, they used to be when I was younger. Now I just have mild cramping.

Has this happened with anyone else? What's going on?